The long term objectives of this project are to understand and delineate the mechanisms underlying "difficult-to-manage asthma", particularly the immunologic responses which distinguish "steroid resistant" (SR) from "steroid sensitive" (SS) asthma, and the role of T lymphocytes in this process. Specific aim one will define the immunologic determinants of SR asthma by assessing the T cell receptor (TCR) Vb gene usage of airway T cells vs peripheral blood T cells in these two forms of asthma, prior to and after a course of prednisone. The DNA sequence of V-D-J segments (functional region) of the expanded TCR b-chains in airway and peripheral blood T cells from SR, as compared to SS, asthmatics will also be delineated. Specific aim 2 will characterize the oligoclonally expanded airway T cells in SR asthmatics by analyzing cytokines produced by Vb-specific T cells. Specific aim 3 will determine the molecular basis for impaired steroid responsiveness in SR asthma. In these experiments, cell extracts of peripheral blood mononuclear cells (PBMC) and airway cells from SS vs SR asthmatics will be assessed for expression of GCRa vs GCR-beta, an endogenous inhibitor of GCR binding. Preliminary data indicate that SR asthma is associated with increased numbers of airway T cells expressing the BV8 T cell receptor gene and increased numbers of T cells expressing the GR-beta isoform associated with steroid resistance. The mechanisms for these abnormalities need further study.